Combustion tube fluid fuel burner



W. J. DUFF COMBUSTION TUBE FLUID FUEL BURNER March 27, 1951 2 Sheets-Shea 1 Filed Feb. 10, 1947 Inventor o m o o o o o o o WALTER J, UF'F March 27, 1951 w. J. DUFF COMBUSTION TUBE FLUID FUEL BURNER 2 Sheets-Shed 2 Filed Feb. 10, 1947 Invenfor WALTER J.

DUF

A llorney Patented Mar. 27, 1951 UNITED STATES PATENT OFFICE 2,546,751 r v COMBUSTION TUBE FLUID FUEL BURNER Walter James Duff, Ilford, England Application February 10, 1947, Serial No. 727,685 In Great Britain February 16, 1946 1 1.; 6 Claims. (o1..'f15s ss) complete combustion is attained thus greatly reducing if not completely eliminating the obnoxious odor normally associated with this type of burner.

A further object of the invention is to provide a burner for apparatus such as cookers or room heaters, with an improved efficiency of combustion by reason of a controlled air flow along the inner perforated wall;

f In this specification the expression combustion chamber is used to denote the space, bounded by the perforated walls.

According to the invention there is provided a burner of the type described in which at least one secondary air passage is provided its inlet being open to atmosphere at the bottom and its outlet extending over and partially closing the upper portion of the combustion chamber so as to direct air across the path of the vapourised fuel which ascends therethrough.

v .Conveniently the shapeof the secondaryair passage is such that its cross sectional area decreases in the direction of the flow of air through that passage to the combustion chamber.

A baffle plate or deflector may, with advantage, be located across the airpassage bounded by the inner perforated wall and in which the baflle plate has slots or apertures'adjacent the said wall and so shaped as .to direct an air. flow along the inner wall. It will be appreciated that in a burner of the type with which the invention is concerned air is induced into the central passage bounded by the inner perforated wall by reason of the flame in the zone of combustion of the burner; with the slotted and drilled baffle plate arrangement an improved efficiency of combustion is obtained and it is thought that this is due to the fact that the air is directed by the slots along the inner perforated wall and that the velocity of this air is greater than it would be with an entirely unobstructed space within the inner perforated wall.

One embodiment of a burner, according to the present invention, will now be described by way .10 cookers or'room heaters, in which substantially of example with refer me to the accompanying drawings.

On the drawings: I

Figure 1 is a sectional elevation of the burner on the line I-I of Figure 4,

Figure 2 is an outside elevation of the burner, Figure 3 is a cross-sectional view on the lin III-III of Figure 1, and

Figure 4 is a plan view of the burner. The burner shown on the drawings comprises two co-aXial perforated cylindrical shells l0 and -l 4 having a short inward taper I2 and I3 at their '1OW6Z ends and located within an outer casing l4 curved inwardly at I5 soas to be closed or partly closed onto the upper periphery of the outer perforated shell I I. The casing I4 extends down below the point where the inward taper [3 on the outer perforated shell commences. The central cylinder 56 formed by the inner perforated shell til is closed at the, top end by a dome I1 and a drilled and slotted deflector plate I8 is fitted ,across the central cylinder I 6 at the point where the inward taper I2 commences at its lower end; the bottom end [9 of the internal cylinder I6 is .open to the air. The slots l8a in the deflector plate or bafile extend round the entire inner face' of the inner perforated shell l0, being interrupted only by the bridge pieces l8b required to support the baffle plate in position. The baffle plate may be flat, convex or concave and preferably also has a central group of circular holes I80. Around the cylindrical casing of the burner is fitted a tapered "shroud 2D, the upper end of which is curved or bent inwards to form a flange 2| which gradually restricts the annular orifice, or outlet 22 from the air duct 23 formed by the shroud external to the burner casing I4 and having its air outlet 22 directed into and across the combustion chamber 'just above the level of the upper periphery of the outer perforated wall II but not above the upper periphery of the inner wall Ill. The lower end of the shroud 20 forming the supplementary "external air duct 23 stops short of the lower end of the burner casing M. The perforated walls or shells Ill and II, the cylindrical burner casing l4 and the outer shroud 20 forming the secondary air passage are secured together by a transverse rod or rods 24, which support the shells, casing and shroud, and maintain them at the appropriate spaced relationship, these rods having flattened ends 25.

The perforated shells Ill and II are mounted over an annular trough 26 having an annular groove or channel 21. This may be filled with absorbent material such as asbestos (not shown),

external air duct 23 and on discharging from theair duct outlet 22 assists in obtaining substane tially complete combustion of the vaporised fuel. By tapering the air duct 23 as shown on the drawing a Venturi efiect isobtained' atthe out.- let 22.

The burner may be covered with a dome 30 of woven wire or other material suitable for forming a'radiant element at its upper end and the inwardly turned outlet=22 of the supplemental air duct 23 may be so proportioned-that the maximum amount of flame issuing from-the combustion chamber at Z is directed against the radiant element so as to produce a considerable area of glow on that element. When the burner is applied'to a cooking apparatus the woven wire cover 30 maybe omitted-and a fixed corrugated or helical wire-3i located in the zone of combustion at the outlet from the space 29 if required.

' The length of the burner casing or chimney l4 and the outer shroud 20 forming the external air duct 23 may be adjusted or adjustable to provide the desired air flow conditions.

I claim:

1. A vaporisingoilburner comprising an annular. fuel trough surmounted by inner and outer perforate walls defining an annular combustion chamber, an imperforate wall surrounding said outer perforate wall anddefiningtherebetween an annular primary air passage open to atmosphere at the bottom and closed at thetop, a second .imperforate' wall surrounding said firstmentioned imperforate' wall and "defining there'- between an annular secondary air passageopen to atmosphere at the. bottom, said imperforate walls being directed radially inwards at the top and extending over and partially closing said combustion chamber to direct the whole ofthe air rising through saidrsecondary air, passage across the path .of and into admixture. with the vaporised fuel within said combustion chamber.

2. A vaporising oil burner, as claimed in claim 11in which said outer, imperforate Wallis conical 3. A vaporising oil burner as claimed in claim 1 in which said trough is of a smaller diameter than and concentric with saidperforate walls, said perforate walls being substantially concentrically flared outwardly and upwardly from said fuel trough and then continue upwards cylindrically, said inner imperforate wall extends downwardly at least as far as said flared portion of said combustion chamber.

4. A vaporising oil burner as claimed in claim 1 in which said trough is of asmaller diameter than and concentric with said perforate walls, said. perforatewalls; being substantially concentrically flared outwardly and upwardly from said fueltrough and then continue upwards cylindrically, and said outer imperforate wall extends downwardly at least as far as said flared portion of said combustion chamber.

5. A vaporising oil burner as claimed in claim 1 in which the said trough is of a smaller diameter than and concentric with said perforate walls, said perforate. walls being substantially concentrically flared outwardly and upwardly from said fuel trough and then continue cylindrically, said imperforate walls extend downward by at least as far as said flared portion of the combustion chamber and the outer of said walls converges inwards and upwards and the inner passage being directed radially inwardsat the top and extending over said combustion chamber whereby to define for the vaporisedfuel" rising through said combustion chamber an outletof smaller cross-sectional'area than-that of the body of said combustion chamber.

WALTER JAMES DUF-F.

REFERENCES 1 CITED The following references are ofyrecord in the file of :this patent:

UNITED STATES PATENTS Number Name Date 500,747 Ruppel July 4; 1893 616,425 Ruppel Dec; 20, 1898 1,523,248- Blackford Jan. 13, 1925 1,582,001 Geammatteo Apr; 20, 1926 1,597,651 Hoffman: Aug. 24, 1926 2,188,577 Richardson Jan. 30, 1940 

